This invention relates to a method of bundling bags such as unfinished shopping bags by heat-adhesion.
Conventional shopping bags are formed of synthetic resin tube by folding both sides of the synthetic resin tube, sealing the bottom and top of the bag by heat, and cutting off the central portion of the top to form a grip portion and opening.
To produce such shopping bags, the following processes are followed. Both sides of the synthetic resin tube are folded in V-shape to make the tube a flat sheet. The strip of the sheet is sealed by heat at predetermined intervals and cut at the sealed portions. The cut bags are stacked and bundled, and delivered to customers such as department stores where the top portions of the bags are cut off and removed to form a grip portion and opening. A number of stacked bags are bundled to facilitate storage and transportation and also to make it possible for the customers to cut off the top portion of as many bags as possible in one cutting operation. In binding the bags into a bundle, it is necessary to have the stacked bags bear tightly on each other to that they will not slip from each other. This is important for the cutting and removal of the top portion of the bags. For this reason, a method of bonding the bags by heat-adhesion has been used. The bonded portions of the bags are later removed during the grip forming process. Conventionally, there are two kinds of heat-adhesion process.
One method is to pierce the heated iron rod through the hole of the stacked bags to bond the bags together at the periphery of the hole by the heat of the iron rod. In this method, however, the temperature of the iron rod becomes low as the iron rod passes through the holes of the stacked bags and therefore no more than 50 bags can be bonded together. Another method is to pierce heated needles through the bags successively and bond them together by the heat of the needles. This method also has a disadvantage that when the number of bags stacked increases, they do not contact tightly, and no more than 50 bags can be bonded together.